It is well-known in the area of computer technology that computer displays used by computers are relatively dim in terms of their luminance or brightness. Conversely, televisions typically comprise relatively bright displays. For example, a typical computer display has a luminance of approximately 50-300 nits (where 1 nit=1 candela/meter2) whereas modern television displays are known to provide luminance of 500 nits or more.
Being aware of this distinction between display types, providers of content (e.g., multimedia data such as audio, graphics, still images or video) for each type of device typically author the content with these display limitations in mind. Thus, for example, video content is created so as to be best viewed on relatively bright displays. On the other hand, computer graphics are authored for relatively low level displays. However, when computer graphics are instead provided on a television display, they often appear too bright. Likewise, when content authored for a television display is instead displayed on a computer monitor, the resulting presentation is typically too dark for ideal viewing. This latter problem is compounded in those situations where video is provided on a computer display against a backdrop of other content that is otherwise intended to be displayed on a computer monitor. This is shown in FIG. 1, which illustrates an exemplary display image 104 on a display 102 in accordance with prior art techniques. In particular, FIG. 1 illustrates a display of a document D1 and an application A1 that, for purposes of this example, are assumed to be authored for viewing via a (relatively dim) computer display. In this situation, the document D1 and the application A1 will be displayed under optimal viewing conditions. However, the subsequent addition of a second application A2, comprising video or other content normally intended for viewing via a brighter display screen, will likely result in the video content of the application A2 being perceived as too dim, which problem is only exacerbated by the background presence of the document D1 and application A1. With increased opportunities to render traditionally separate types of content (such as video and computer graphics) on a single screen, these disparities are more likely to lead to negative user experiences.
It is known in the art to provide brightness, contrast, white level, backlight or other controls of the luminous output on various types of displays (hereafter referred to as brightness controls). However, users are unlikely to switch brightness levels using such controls as they move between different applications on a computer. Furthermore, such controls do not provide the ability to mix brightness levels within a single displayed image. In this same vein, various types of displays with adjustable backlight levels may be controlled to adjust the overall brightness of the display screen. Once again, these are typically restricted to controlling the overall brightness of the entire screen, and typically do not provide separate control over portions of the screen. Likewise, adjustments to these backlight levels are typically provided based on changes in power state of the device or explicit user input.
More recently, developers of liquid crystal display (LCD) technology have developed techniques that allow the displays themselves to adjust the brightness of certain regions within the display based on knowledge about the inputs being provided to the display. For example, such systems take advantage of techniques such as so-called “picture in picture” (PIP) which provide the monitor with data regarding where video content is to be displayed. In this manner, the display can adjust intensity of a backlight to be optimally bright for the video display, and thereafter adjust presentation of other regions on the screen to accommodate the adjusted intensity of the backlight. In a similar vein, such monitors may be provided with controls that allow the user to define a region on the display that is thereafter controlled in a similar manner. Not only do these solutions increase the cost and complexity of such displays, they are relatively limited in their ability to adapt to changes in content as they are displayed.
It would therefore be advantageous to provide a technique that allows for the flexible adjustment of brightness of portions of a display image based on content types without adding to the cost or complexity of displays.